Contact lens extraction/hydration systems and methods of reprocessing fluids used therein

ABSTRACT

The present contact lens treating systems and methods effectively remove extractable materials from contact lenses, for example, newly formed contact lenses, so that the lenses can be safely and conveniently worn, for example, for extended periods of time. Such treatment methods and the present extraction medium reprocessing methods allow lens treatment while reducing extraction medium losses, thereby reducing costs of these materials and the burden of such treatment on the environment. The present methods can also be useful for manufacturing a heat stabilized contact lens, for example, a water swelled contact lens including a Vitamin E component which is insoluble in the lens in a hydrated state.

The present invention relates to methods for making and treating contactlenses and methods for reprocessing fluids used in treating contactlenses. More particularly the invention relates to methods for makingand treating contact lenses to remove undesirable extractable materialsfrom the contact lenses prior to packaging the lenses and prior to useof the lenses by an individual, and to methods for reprocessing, forexample, for reuse, fluid materials, such as extraction media, aqueousmedia and the like, used in the treatment of contact lenses.

BACKGROUND OF THE INVENTION

Contact lenses, particularly newly molded contact lenses, often areprocessed using one or more fluids, for example, liquids to removeundesirable components from the lenses prior to packaging of the lenses.To illustrate, newly formed polymeric contact lenses, such as silconehydrogel contact lenses or contact lenses which comprise a siliconehydrogel material, often contain unreacted monomers which are removed byextracting the monomers from the lenses with a liquid medium, such as anon-aqueous liquid medium or an organic solvent. After the extractionprocessing, the contact lens is contacted with an aqueous liquid mediumto hydrate the lens, for example, to swell the lens with water.

During such fluid processing, relatively large amounts of fluids, suchas solvents, are used and are discarded. This represents a substantialcost in contact lens manufacturing. In addition, discarding or disposingof such large amounts of solvents can be an environmental concern andpresent risks to people handling the solvents and involved in theextraction processes.

In addition, contact lenses including hydrophilic polymeric materialsare often subjected to elevated temperatures, for example, duringsterilizing, packaging, cleaning, disinfecting and the like processing.Such elevated temperatures may result in damage, for example,discoloring, weakening and/or other damage and the like, to the contactlenses.

Thus, there remains a need for systems and methods which effectivelyextract undesirable components, such as unreacted monomers, from thecontact lenses, such as silicone hydrogel contact lenses, and hydratesuch extracted contact lenses, and which are cost effective and safe touse. There also remains a need for systems and methods to enhance theheat stability of the contact lenses or lens materials to reducedeleterious effects of elevated temperatures to which such lenses areexposed.

SUMMARY OF THE INVENTION

New systems and methods for treating contact lenses and methods forreprocessing extraction medium used in treating contact lenses have beendiscovered. The present contact lens treating systems and methods areeffective in removing extractable materials, such as unreacted monomersor monomeric components, from contact lenses, such as silicone hydrogelcontact lenses. Unlike systems and methods for cleaning contact lensesafter they have been worn on an eye, the present systems and methods areused to extract and hydrate or otherwise treat newly formed, forexample, newly molded, contact lenses prior to the lenses beinginitially packaged, so that the lenses can be safely and comfortablyworn on the eye, for example, for extended periods of time. The presenttreatment systems and methods and the present extraction mediumreprocessing methods generally utilize stepwise processing of lenses toobtain effective and efficient removal of extractable materialstherefrom. In addition, the methods provide for highly efficient andeffective recycling of extraction medium thereby reducing contact lensmanufacturing costs as well as burden of these materials on theenvironment and the risk to people involved in the treatment of contactlenses.

The present methods are relatively straightforward to practice, whileproviding lens wearing benefits, economic benefits, and environmentalbenefits.

In a broad aspect of the present invention, methods for treating contactlenses are provided which comprise:

(a) contacting a swellable, for example, liquid swellable, polymericcontact lens containing extractable material with an extraction medium,for example, a liquid extraction medium other than pure water, atconditions effective to swell the contact lens with the extractionmedium, to reduce the amount of extractable material in the contactlens, and to form a used extraction medium containing extractablematerial;

(b) contacting the contact lens having a reduced amount of extractablematerial with water to form a water swelled contact lens;

(c) processing the used extraction medium to produce a reprocessedextraction medium having a reduced concentration of extractable materialrelative to the used extraction medium; and

(d) using the reprocessed extraction medium as at least a portion of theextraction medium in step (a).

The present methods of treating contact lenses may be used with anyswellable, polymeric contact lenses, for example and without limitation,conventional so-called hydrogel polymeric contact lenses, hydrophilicpolymeric contact lenses substantially free of silicon, otherhydrophilic polymeric contact lenses and the like. The present methodsare very usefully employed to treat contact lenses which comprise ahydrophilic silicon-containing polymeric material, for example, suchmaterials as are used in contact lenses commonly referred to as siliconehydrogel contact lenses. As the term implies, a swellable, polymericcontact lens is a polymeric contact lens which is capable of becomingswelled with a medium, such as a liquid medium, for example, theextraction medium, one or more other fluid media used in accordance withthe present invention, aqueous medium, water and mixtures thereof. Forexample, when fully hydrated, such swellable contact lenses may includebetween about 15% or about 20% to about 50% or about 80% by weight ofwater, for example, at equilibrium conditions.

Step (a) of the present methods may be repeated, for example, at leastonce or at least twice or more. In one very useful embodiment, theextraction medium includes less than about 15% by weight of water orless than about 10% by weight of water or less than about 5% by weightof water.

In a very useful embodiment, step (a) of the present methods isconducted at conditions so that the amount of extractable material inthe contact lens is reduced by at least about 50% or at least about 70%or at least about 90% or more.

In one very useful embodiment, step (a) of the present contact lenstreating methods includes contacting the contact lens with a firstextraction medium portion and, thereafter, contacting the contact lenswith a second extraction medium portion having a reduced concentrationof water relative to the first extraction medium portion. Thisprocessing sequence of step (a) is advantageous in reducing the stresson contact lenses being processed. Such contact lenses often are atleast partially hydrated, that is, are at least partially swelled withwater. Using an initial extraction medium which includes some amount ofwater, such as 5% to 15% water, reduces the stress on, and, therefore,reduces the risk of damaging, the contact lens in going from asubstantially water environment to a substantially non-aqueousextraction medium environment, such as a solvent based environment thatcomprises 1% or less water. Such processing sequence also takes intoaccount the fact that the non-aqueous portion of the extraction mediumis very effective in removing extractable materials from the contactlens, such as organic materials including unpolymerized monomers and thelike. Thus, for extraction effectiveness/efficiency, it is advantageousthat the contact lens be contacted at least once with an extractionmedium which is substantially non-aqueous, such as a solvent or organicsolvent based medium. In one embodiment, the contacting of the contactlens with second extraction medium portion having a reducedconcentration of water, or a greater concentration of organic solvent,is repeated, for example, repeated at least once or at least twice ormore.

As noted above, the extraction medium is a medium other than pure water.For example, the extraction medium may include at least one componenteffective to solubilize extractable material contained in the contactlens. Such component often is a non-aqueous component. Any suitablenon-aqueous component or components may be included in the presentextraction medium provided that each such component or components iseffective in at least facilitating the removal of extractable materialfrom the contact lens and can be removed from the lens to avoid anysignificant or undue detrimental effect on the contact lens or on thewearing of the contact lens or on the wearer of the contact lens.

In one embodiment, the extraction medium comprises at least one organiccomponent, for example and without limitation, an alcohol component,with the organic component being effective to solubilize at least aportion of the extractable material in the contact lens.

In one particularly useful embodiment, the extraction medium comprisesan alcohol selected from the group consisting of methanol, ethanol,propanol (1-propanol and/or isopropanol) and the like and mixturesthereof. Examples of such mixtures include, without limitation, ethanoland methanol; ethanol and propanol and the like. For example, theextraction medium may comprise a major amount by weight of ethanol on awater free basis. As used herein, the term “a major amount” refers to anamount equal to at least about 50%. In one very useful embodiment, theextraction medium comprises at least about 80% by weight or at leastabout 90% by weight or at least about 95% by weight of ethanol on awater free basis.

Advantageously, prior to step (b), the contact lens is contacted with acomposition containing more than about 5% by weight of water and anorganic solvent component. This feature of the present inventionfacilitates allowing the lens to be transitioned from a substantiallynon-aqueous extraction medium environment to a substantially aqueousenvironment in which the lens is hydrated and prepared for packaging. Inother words, the contacting with a composition containing more thanabout 5% by weight of water reduces the stress on the lens, andtherefore reduces the risk of damaging the lens, in going from asubstantially extraction medium environment to a substantially aqueousenvironment. The composition containing more than about 5% by weight ofwater may contain up to about 20% or up to about 40% or up to about 60%by weight of water. For example, one measure of lens stress is theamount of lens expansion which occurs in going from a substantiallyextraction medium environment to a substantially aqueous environment. Toillustrate, for some contact lenses made of a hydrophilicsilicon-containing polymeric material the following relationship betweenenvironment and % diameter expansion of the lens has been found:

% Expansion of Environment Lens Diameter 100% by wt. Deionized Water 0 50% by wt. deionized Water 24  50% by wt. ethanol/methanol blend(industrial methylated spirits ‘‘IMS’’)  15% by wt. Deionized Water 54 85% by wt. IMS 100% by wt. IMS 100

By moving from a substantially extraction medium environment to asubstantially aqueous environment in more than one step, as set forthherein, the lens is allowed to contract at a slower rate, therebyreducing stress on the lens.

In the present methods of treating contact lenses, step (b) may beadvantageously repeated, for example, repeated at least once or at leasttwice or more. Repeating step (b) facilitates producing a contact lensproduct which is substantially free of any non-aqueous material presentin the extraction medium.

In another broad aspect of the present invention, methods forreprocessing an extraction medium used in removing extractable materialfrom a polymeric contact lens are provided. Such methods comprise:

(1) contacting a used extraction medium other than pure water containingan amount of water and extractable material from a polymeric contactlens with an extraction medium having substantially no extractablematerial at conditions effective to produce a first product having areduced content of water and a reduced content of the extractablematerial relative to the used extraction medium; and

(2) contacting at least a portion of the first product with theextraction medium at conditions effective to produce a second producthaving a reduced content of water relative to the first product.

In a very useful embodiment, the present methods may comprise contactinga portion of the first product with a polymeric contact lens containingextractable material at conditions effective to remove at least aportion of the extractable material from the contact lens. Thiscontacting forms a first contact lens product having a reduced amount ofextractable material relative to the polymeric contact lens prior to thecontacting with the first product, and forms at least a portion of theused extraction medium. As used herein, a contact lens product, such asa first contact lens product, a second contact lens product, etc.,refers to a contact lens at different stages of extraction (e.g., atdifferent stages where the contact lens contains different amounts ofextractable components). It can be understood that the use of thephrases first, second, third, etc. contact lens products refers to acontact lens that has reduced amounts of extractable components as itproceeds through the present systems.

In one embodiment, the present methods further comprise contacting atleast a portion of the second product with the first contact lensproduct at conditions effective to extract an additional amount of theextractable material from the first contact lens product. Thiscontacting forms a second contact lens product having a reduced amountof extractable material relative to the first contact lens product andforms another portion of the used extraction medium.

In yet a further embodiment, the present methods further comprisecontacting at least a portion of the second product with the secondcontact lens product at conditions effective to extract a further amountof the extractable material from the second contact lens product. Thiscontacting forms a third contact lens product having a reduced amount ofextractable material relative to the second contact lens product, andalso forms a further portion of the used extraction medium.

In a further embodiment, the present methods further comprise contactinga portion of the first product with the second contact lens product inthe presence of water at conditions effective to partially hydrate thesecond contact lens product. This contacting forms a first hydratedcontact lens and an additional portion of the used extraction medium.

Alternately, the present methods further comprise contacting a portionof the first product with the third contact lens product in the presenceof water at conditions effective to partially hydrate the third contactlens product. This contacting forms a first hydrated contact lens and astill further portion of the used extraction medium.

In a particularly useful embodiment, the present methods furthercomprise, prior to step (1), contacting at least a portion of the usedextraction medium with a filter medium at conditions effective to removecontact lens debris and/or other solid and/or semi-solid materials, fromthe used extraction medium. In another embodiment, the present methodsprovide that step (1) includes contacting at least a portion of the usedextraction medium with a removal medium, such as an activated removalmedium, for example, activated carbon, at conditions effective to removeat least a portion of the extractable material from the used extractionmedium.

The present methods may include the above-noted contacting with a filtermedium and contacting with a removal medium together. In such anembodiment, the filter medium contacting preferably occurs prior to theremoval medium contacting.

Thus, it can be understood that the present systems provide forrecycling of the extraction media, including media that comprise anorganic component such as an organic solvent, in connection withextracting unreacted components and the like from polymeric contactlenses. This is in contrast to existing systems which dispose of theorganic solvents after extraction. The extraction media is filtered asneeded to remove particulate matter and/or the extracted components fromthe contact lens. The filtered extraction media can then be mixed with“fresh” extraction media to provide a volume of extraction mediacontaining a desired amount of water and effective in extractingextractable components from the newly polymerized contact lenses.

In yet another broad aspect of the invention, contact lenses areprovided having enhanced heat stability, for example, enhanced abilityto withstand elevated temperatures. The present contact lenses are safeto be worn in/on the eyes of humans and animals. Moreover, the presentcontact lenses can be produced using methodologies which arestraightforward and easy to practice. In short, the present contactlenses provide substantial heat stability benefits, and can be producedrelatively easily and cost effectively.

In this aspect of the invention, contact lenses may comprise a waterswellable, polymeric lens body and a heat stabilizer component combinedin the lens body in an amount effective to increase the heat stabilityof the contact lens relative to an identical contact lens without theheat stabilizer component. In one embodiment, the heat stabilizercomponent is insoluble in the lens body in a hydrated state. In oneembodiment, the heat stabilizer component comprises a Vitamin Ecomponent or Vitamin E.

In a very useful embodiment, the lens bodies of the present contactlenses comprise a hydrophilic silicon-containing polymeric material anda Vitamin E component. The Vitamin E component in the present lenses isuseful as a heat stabilizer component and is insoluble in the lens bodyin a hydrated state, that is, when the lens body is swelled with water.Preferably, the heat stabilizer component, for example, the Vitamin Ecomponent, is soluble in a non-aqueous liquid, for example, an alcoholcomponent, such as that selected from methanol, ethanol, propanol, andthe like and mixtures thereof. The presence of the Vitamin E componentwill be determined based on the hydrophilic silicon-containing polymericmaterial and the lens produced with such material. For example, somehydrophilic silicon-containing polymeric materials may have an adequateheat stability without an additional Vitamin E component, whereas otherhydrophilic silicon-containing polymeric materials may benefit from thepresence of a Vitamin E component.

In one embodiment, the Vitamin E component is selected from Vitamin E,salts of Vitamin E, derivatives of Vitamin E, and mixtures thereof. In avery useful embodiment, the Vitamin E component comprises Vitamin E.

In a further broad aspect of the present invention, methods of heatstabilizing a water swellable contact lens are provided. Such methodscomprise contacting a water swellable contact lens with a materialcomprising a carrier component other than pure water, and a heatstabilizer component soluble in the carrier component and insoluble inthe contact lens in a hydrated state. The contacting is effective toswell the contact lens with the material. The material swelled contactlens is contacted with water at conditions effective to replace at leasta portion, for example, a major portion, and even substantially all, ofthe carrier component in the contact lens with water, thereby forming awater swelled contact lens including an effective amount of the heatstabilizer component.

In the present methods, the contact lens advantageously comprises ahydrophilic polymeric material, for example, a hydrogel-formingpolymeric material, a hydrophilic silicon-containing polymeric materialand the like. In one embodiment, the heat stabilizer component comprisesa Vitamin E component. The carrier component comprises a non-aqueouscomponent, for example, an alcohol component. The carrier componentpreferably includes a material selected from methanol, ethanol, propanoland the like and mixtures thereof.

Any and all features described herein and combinations of such featuresare included within the scope of the present invention provided that thefeatures of any such combination are not mutually inconsistent.

These and other aspects and advantages of the present invention areapparent in the following detailed description, claims and drawings inwhich like parts bear like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow diagram of one embodiment of the presentinvention.

FIG. 2 is a schematic flow diagram of another embodiment of the presentinvention.

DETAILED DESCRIPTION

The present invention is very useful in treating swellable polymericcontact lenses, for example, contact lenses comprising hydrophilicpolymeric materials, and in reprocessing the fluid materials used totreat such lenses. Such contact lenses are often described as beingswellable contact lenses in that during use of such contact lenses thelenses include sufficient amounts of water to be swelled by such water.For example, such contact lenses often include about 10% or about 15% orabout 20% to about 50% or about 60% or about 80% by weight of water inan equilibrium state, for example, when being worn on an eye. Suchcontact lenses are often referred to as soft hydrophilic contact lensesor hydrogel contact lenses. In one particularly useful embodiment, thecontact lenses include hydrophilic silicon-containing polymericmaterials. The contact lenses to be treated are often produced usinghydrophilic monomeric materials, that is hydrophilic monomers, forexample, together with one or more other monomers, which are polymerizedin forming the contact lenses.

The present invention is very useful during the later stages of contactlens manufacturing. For example, the present invention is useful intreating contact lenses which have been recently formed, for example, bypolymerization of one or more monomers. Such recently formed contactlenses often include amounts of extractable materials, such as one ormore monomeric components which have failed to react or failed to reactcompletely during the polymerization processing and/or other extractablematerials present in such lenses. In order to provide contact lensessuitable for safe and effective wear in the eyes of humans or animals,such recently formed contact lenses advantageously are treated to removesuch extractable materials. The present systems and methods are usedprior to the initial packaging of contact lenses in sealed packages,such as blister packs and the like. Thus, the present systems andmethods are used prior to the lenses being worn on an eye, and can bedistinguished from methods of cleaning contact lenses after placement onan eye of an individual.

The present invention is directed to processing which is effective toremove such extractable materials from contact lenses and providecontact lenses which are safe and effective in use. The invention isalso related to reprocessing the fluids, for example, liquid, materialsused in treating such contact lenses to provide substantial benefits,for example, reduced costs, reduced adverse environmental impacts ofsuch contact lens treating and the like. In addition, the presentinvention is directed to methods of heat stabilizing a water swellablecontact lens, and to contact lenses that include heat stabilizingcomponents.

Embodiments and aspects of the present invention are illustrated in, andwill be described with reference to, FIG. 1. However, it should beunderstood that the present invention is not limited to the embodimentsand aspects shown in FIG. 1, and that any and all embodiments of andmodifications consistent with the present methods as set forth hereinare included within the scope of the present invention.

As used herein, the term “extraction medium” includes any suitablematerial, other than pure water, which is useful to reduce the amount ofextractable material included in and/or on a contact lens being treatedin accordance with the present invention. The extraction medium oftenincludes a non-aqueous component effective to solubilize extractablematerial in and/or on the contact lens, and/or to otherwise combine withsuch extractable material so that such extractable material is removedor extracted from the contact lens being treated. Examples ofnon-aqueous components which may be included in the present extractionmedia include, without limitation, components, such as organiccomponents, that are effective in reducing the amount of extractablematerial in the contact lenses being treated and, in addition, have nosignificant or undue detrimental effect on the contact lens beingtreated, on the wearing of the contact lens, or on the wearer of thecontact lens.

In one embodiment, the extraction medium includes at least one alcohol,for example and without limitation, at least one alkanol. The extractionmedium may include an alcohol selected from the group consisting ofmethanol, ethanol, propanol and the like, and mixtures thereof.

In one very useful embodiment, the extraction medium comprises a majoramount by weight of ethanol, such as a mixture of about 97% by weight ofethanol and about 3% by weight of methanol. An example of a usefulextraction medium is industrial methylated spirits (IMS), which istypically about 99.7% by weight water free. It should be noted that theextraction medium may also include an amount of water, preferably aminor amount of water, that is less than about 50% by weight of water.

With reference to FIG. 1, newly formed swellable, polymeric contactlenses, for example, such lenses containing a hydrophilic,silicon-containing polymeric material, are processed in system 10. Suchlenses are provided to first stage 12 of system 10. These lenses includeunreacted monomers, and possibly other extractable material, which areto be removed before the lenses can be packaged for shipment/sale.

Each of the stages referred to herein includes a tank which is sometimesreferred to by the same reference numeral as the stage in which it isincluded. Each such tank defines a chamber in which contacting betweenthe lenses being treated and a liquid medium, as described herein,occurs.

In first stage 12, the lenses are contacted with a liquid compositioncontaining about 80% to about 95% IMS and about 5% to about 20% byweight of water. Such contacting occurs at a temperature in a range ofabout 20° C. to about 50° C. The operating temperatures of first stage12, as well as second, third, fourth, fifth and sixth stages 16, 20, 24,26 and 28, described hereinafter, are in a range of about 20° C. toabout 50° C. In certain embodiments, the stages are operated at roomtemperature. These stages are enclosed within the same module orenclosure for safety reasons. Seventh and eighth stages 30 and 32,described hereinafter, are operated at less than about 25° C. forexample, at ambient or room temperature.

The contacting between the contact lenses and the liquid composition infirst stage 12, as well as the contacting between the contact lenses andthe other liquid compositions/liquid materials in the other stagesdescribed herein, is conducted for a period of time effective to obtainthe desired degree of mass transfer, and advantageously effective toprovide cost effective and efficient treatment of the contact lenses.Excessively short contacting times may require additional stages toachieve the desired results. Such additional stages are costly and mayinvolve excess handling or moving of the lenses, with an increased riskof damaging the lenses. On the other hand, excessively long contactingtimes may require larger contacting vessels and more processing fluids,each of which involves additional costs. In one embodiment, contactingtimes are in a range of about 0.1 hour or about 0.2 hour or about 0.4hour to about 0.6 hour or about 1 hour or about 2 hours or more. In theembodiment shown in FIG. 1, the contacting of the lenses and the liquidcomposition in first stage 12 occurs for about 45 minutes. This time canbe adjusted, if necessary to achieve the desired result.

In addition, ultrasonic energy, produced using a conventional ultrasonicenergy generator, may optionally be applied to the liquid composition inthe first stage 12 to facilitate intimate contacting between the liquidcomposition and the contact lenses in first stage 12. In one embodiment,such intimate contacting between the liquid composition and contactlenses is facilitated through continuous liquid composition agitationfrom the continuous topping up of the tank in stage 12 and continuousdraining of the liquid composition from the tank via a conventional weirsystem.

In any event, intimate contacting between the liquid composition and thecontact lenses is obtained in first stage 12 so that the lenses becomeswelled with the liquid composition and mass transfer occurs between thelenses and the liquid composition. Some of the extractable materialoriginally in or on the lenses is removed from the lenses in first stage12 and is present in the liquid composition outside the lenses.

During and after such contacting, the liquid composition in first stage12 may optionally be pumped through a first activated zone 14 whichcontains activated carbon. The liquid composition from the first stage12 may be passed through the activated carbon in first activated zone 14and passed back into first stage 12. The activated carbon in firstactivated zone 14 removes some of the extractable material which isremoved from the contact lenses in first stage 12, and thus helps toprolong the effectiveness of the liquid composition in first stage 12.

First stage 12, like the other stages described hereinafter (unlessexpressly stated otherwise) may be equipped with at least one pump, forexample, of conventional design, to pass the liquid in first stage 12through first activated zone 14 and/or to pump the liquid out of firststage 12 for reprocessing, for example, if the lens treating whichoccurs in the stage is conducted in a batch-wise mode with respect tothe treating liquid or liquids being employed as is described elsewhereherein. Such pumping action also facilitates intimate contacting betweenthe liquid and contact lenses in first stage 12. In addition, each ofthe stages, unless expressly stated otherwise, may employ ultrasonicenergy, as described with regard to first stage 12, to facilitateintimate contacting between the liquid and contact lenses in such stage.

Lens processing in first stage 12, and unless expressly statedotherwise, in each of the other stages, is batchwise with respect to thecontact lenses being treated. In other words, a batch of contact lensesis processed in one stage, for example, first stage 12. After completionof processing in the one stage, the batch of lenses, for example, insuitably stacked trays and lens holders, are moved to the next stage forfurther processing. This is continued until the batch of lenses has beenprocessed in each of the stages, as described herein. Examples of usefultrays include color coded trays that have openings to provide contactbetween contact lenses located on the trays and the liquid compositions.Color coded trays may be useful to facilitate visualization of theindividual lens located thereon. For example, the trays may comprise acolor component that contrasts with a tint of the contact lens to makethe lens relatively easy to see by a person. The trays are designed tobe stacked upon each other. For example, a first tray and asubstantially identical second tray can be stacked together to form atray assembly. The first tray includes a plurality of wells, each wellbeing structured to contain a single contact lens. The second tray canbe placed over the first tray to act as a lid for the first tray and tofurther hold contact lenses in the wells of the second tray. Stacks oftrays, such as stacks of 4, 8, 16, 32, or more trays can be provided inone or more carriers that can be used to transfer the lenses among thedifferent stages of the present systems.

In one embodiment, the liquid composition in stage 12, as well as theliquid medium being used in each of the other stages, unless expresslynoted to the contrary, is continuously replenished, for example, fromline 76, as described hereinafter, and excess (used) liquid compositionis continuously passed out of stage 12, for example, is passed over aconventional weir or dam-like device out of first stage 12, through line34, for reprocessing. In this embodiment, the lens treating can be saidto be continuous with respect to the liquid composition being used instage 12.

In an alternate embodiment, the liquid composition in first stage 12, aswell as the liquid medium being used in each of the other stages, unlessexpressly noted to the contrary, is maintained in service until itschemical make-up is deemed to no longer be suitable to perform itsfunction in first stage 12. When the liquid medium is deemed no longersuitable, it is removed from stage 12 as a single batch, and replaced bya new batch of reprocessed liquid composition. This type of operationcan be considered to be batchwise operation with respect to the liquidmedium used to treat the contact lenses.

The chemical make-up of this liquid composition can be monitored, forexample, for IMS and/or water and/or extractable material content.Alternatively, or in addition, based on experience with an individualsystem, the liquid composition in first stage 12 may be used to treat acertain number of batches of lenses, for example, 1 or 2 or 3 batches oflenses to about 5 or about 7 or more batches of lenses, before beingremoved and replaced.

In any event, the used liquid composition is removed from first stage 12for reprocessing and replaced with a reprocessed liquid composition, asis described elsewhere herein. The liquid compositions/materials in theother stages are used/removed/replaced continuously or batch-wise inmuch the same manner as described herein with regard to the liquidcomposition in stage 12.

After about 45 minutes, the contact lenses are removed from first stage12 and placed in second stage 16. The contact lenses are contacted insecond stage 16 with a liquid composition containing IMS at aconcentration of greater than about 95% by weight, the remainder of theliquid material being water, for about 45 minutes. Contacting times mayrange in second stage 16, as well as in all the other stages describedherein as described with regard to the contacting in stage 12.Conventional heating elements may be employed, for example, external tothe walls of the second stage 16, which can be insulated for energyefficiency, to maintain the desired temperature.

The concentration of IMS is increased between first stage 12 and secondstage 16 The original, newly formed contact lenses are at leastpartially hydrated with water. In first stage 12, this water is replacedwith the liquid composition in first stage 12. These lenses are thenpassed to second stage 16 where they are swelled with a liquid materialhaving a higher concentration of IMS. Allowing the newly formed,hydrated lenses to pass through first stage 12 before being exposed to ahigh concentration of IMS in second stage 16 reduces the stress to whichthe lenses would be exposed if they were to be passed directly from anaqueous environment to the high IMS concentration environment. The highconcentration of IMS in second stage 16 is very effective in removingextractable material from the contact lenses.

Second activated zone 18 may optionally be provided so that the liquidmaterial in the second stage 16 can be passed through activated carbonin second activated zone 18, and back to second stage 16, to removeextractable material in the liquid material from second stage 16, and tohelp prolong the effectiveness of the liquid material in second stage 16

After about 45 minutes of contacting, the contact lenses are removedfrom second stage 16 and placed in third stage 20.

Third stage 20 provides for further contacting the contact lenses with aliquid material containing IMS at a concentration greater than 95% byweight. In effect, the contacting in the third stage 20 is a repeat ofthe contacting in second stage 16 The liquid material from third stage20 may optionally be passed to third activated zone 22 containingactivated carbon. The liquid material from third activated zone 22 ,witha reduced concentration of extractable material, is returned to thirdstage 20.

This contacting in third stage 20 occurs for a period of time of about45 minutes.

The contact lenses are removed from third stage 20 and include lessextractable material than the contact lenses removed from second stage16.

In some embodiments, the contact lenses are then placed in fourth stage24 containing a liquid composition containing IMS at a concentration ofgreater than 95% by weight and about 50 to about 200 ppm by weight ofVitamin E. Vitamin E, which is soluble in this liquid composition in thefourth stage and insoluble in water, is used to enhance the heatstability of the contact lenses being processed. The temperature of thecontacting in forth stage 24 is in a range of about 20° C. to about 50°C. This contacting occurs for about 45 minutes.

In some embodiments of the present invention, Vitamin E is not employed.One such embodiment not employing Vitamin E is described hereinafterwith respect to FIG. 2.

Still referring to FIG. 1, the contact lenses removed from fourth stage24, including an effective amount of Vitamin E, are placed in fifthstage 26 for contact with a liquid composition including about 50% byweight IMS and about 50% by weight deionized water. This contactingoccurs at a temperature between 20° C. and 50° C., for example, similarto the temperature of first stage 12, for about 45 minutes. This is atransition stage from about 95% by weight IMS to less than about 5% byweight IMS, and it reduces the stress on the lens from the associatedshrinkage, as described elsewhere herein.

The contact lenses removed from fifth stage 26 are then placed in sixthstage 28 where the lenses are contacted with deionized water at lessthan about 20° C. to about 50° C.

After 45 minutes of contacting, the contact lenses are emoved from sixthstage 26 and placed in seventh stage 30, where the lenses are againcontacted with deionized water at a temperature of less than about 25°C., for example, similar to the temperature of first stage 12. Suchcontacting occurs for about 45 minutes.

The contact lenses are removed from seventh stage 30 and placed ineighth stage 32, where the lenses are again contacted with deionizedwater at a temperature of less than about 25° C. for about 45 minutes.

A final product hydrated lenses removed from eighth stage 32 are readyfor packaging. For example, the hydrated lenses removed from eighthstage 32 may be contacted with a suitable packaging composition, forexample, including a buffer, a tonicity agent and one or more otherconventional materials used in packaging hydrophilic contact lenses.

The above description has, to a large extent, followed the path ofcontact lenses from being freshly removed from molding cups or moldsections to being hydrated lenses ready for packaging. The followingdescription follows the processing and reprocessing of the extractionmedia and deionized water used in treating the lenses.

Again, with reference to FIG. 1, on a continuous basis, or batchwise,after it is determined, for example, by monitoring the chemical make-upof the liquid composition in first stage 12, that this used or spentcomposition is no longer suitable for effective/efficient functioning infirst stage 12 and, therefore, is to be removed and replaced, the liquidcomposition from first stage 12 is passed (continuously weired or pumpedbatchwise) out of first stage 12 and passed through line 34, into commonline 36. Similarly, the used or spent liquid material from second stage16 is passed out of second stage 16 and is passed through line 38 intocommon line 36; the used or spent liquid material from third stage 20 ispassed out of third stage 20 and is passed through line 40 into commonline 36; the used or spent liquid composition from fourth stage 24 ispassed out of fourth stage 24 and is passed through line 42 into commonline 36; and the used or spent composition from fifth stage 26 is passedout of fifth stage 26 and is passed through line 34, into common line36.

It is to be understood that each of the liquid compositions/liquidmaterials can be removed from its respective stage independently ofremoving one or more of the other of such liquid compositions/liquidmaterials from one or more of the other stages. Such removal or removalsadvantageously are accomplished so as to avoid any substantial, or evensignificant, interference with or disruption of the treating of thecontact lenses, for example, as described elsewhere herein. The qualityof the liquid composition/material may be measured and can be changed byautomatic monitoring and replenishment. For example, if theconcentration of IMS has dropped in first stage 12 below a specifiedlower limit, the rate of IMS replenishment could be increased toincrease the concentration of IMS in that stage. In addition, areprocessed liquid composition/liquid material is provided continuouslyor batchwise to such stage, as is discussed elsewhere herein. In thismanner, the treating of contact lenses can continue without undue delay.

The liquid passing through common line 36 is brought into contact with aconventional micro porous filter medium in filter zone 50 .This filterzone 50 is designed to remove lens debris and other solid or semi-soliddebris and/or extraneous material from the system 10. Periodically, asneeded for effective/efficient operation, the spent filter medium fromfilter zone 50 is discarded and replaced with fresh filter medium.

The filtered liquid is passed from filter zone 50 through line 52 intocommon activated line 54 where the liquid is contacted with activatedcarbon to remove extractable material (previously removed from thecontact lenses) from the liquid which is then passed through line 55 toa storage tank 56.

The liquid from storage tank 56 is passed through line 58 intodistillation zone 60 where the liquid is separated into an eutecticcomposition containing about 95% by weight IMS and about 5% by weight ofwater, and an aqueous waste product, which is properly disposed of afterbeing removed from distillation zone through line 62.

Distillation zone 60 comprises a conventional, and advantageously fullyautomatic, distillation apparatus in which a low boiling material, suchas the composition containing about 95% by weight IMS, is the overheadproduct, and the higher boiling material, such as the aqueous wasteproduct, is removed from the bottom of the apparatus. Since thedistillation apparatus of distillation zone 60 may be conventional, itsstructure and operation is well within the skill of the art. Therefore,a detailed description of such structure and functioning is notpresented herein.

A portion of the liquid containing about 95% by weight IMS is passedthrough line 64 into storage line 66.

The remainder of the liquid containing about 95% by weight IMS fromdistillation zone 60 is passed through line 68 into a drying device 70to remove water from this liquid and produce a product liquid having atleast about 99% by weight IMS. This product liquid containing at leastabout 99% IMS is passed through line 72 to storage tank 74.

Drying device 70 may be of conventional construction, and isadvantageously at least partially or even fully automated. For example,the drying device 70 may include a chamber filled with desiccantparticles which remove water from a water-containing liquid being passedthrough the chamber. The spent particles, that is water-containingparticles which can no longer effectively/efficiently remove water fromthe water-containing liquid in device 70, can be removed from dryingdevice 70 and replaced. Alternatively, such particles can be treated,for example, at elevated temperatures, to drive off water and restorethe ability of the particles to effectively/efficiently remove waterfrom the water-containing liquid in device 70. Such drying devices andthe particles useful in such drying devices are well known to thoseskilled in the art. Therefore, no detailed description of such devicesand particles are presented here.

In one very useful embodiment, the drying device 70 used is a membraneseparation or pervaporation device. The larger molecules of IMS passover a micro porous membrane to be reused while the smaller watermolecules are forced through to waste. Therefore, a further wastestream, shown passing through line 71, is generated by the drying device70 for disposal.

A quantity of fresh liquid IMS is added to storage tank 74. This freshIMS is added to make up for the IMS that is lost during the treating ofthe contact lenses and the reprocessing of the liquids used in suchtreating. One important advantage of the present invention is thatreduced amounts of IMS (extraction medium) are required to treat thecontact lenses because of the liquid reprocessing in accordance with theinvention.

As shown in FIG. 1, the liquids in storage tanks 66 and 74 are passed tothe individual stages 12, 16, 20 , 24 and 26 to provide the desiredliquid composition/liquid material for each such stage. For example, theliquid having about 95% by weight IMS from storage tank 66 is passedthrough line 76 to first stage 12 and through line 78 to fifth stage 26.The liquid having about 99% by weight IMS from storage tank 74 is assedto second, third and fourth stages 16, 20 and 24 through lines 80, 82and 84 respectively.

The combination of filtration, activated carbon contacting,distillation, and drying, together with separate storage of differentliquids having different IMS concentrations, provide for very effectiveremoval of extractable material from the contact lenses and, at the sametime, because of the reprocessing of the liquid compositions/materialsas noted above, reduces the overall amount of IMS required to performsuch treating.

In addition, as illustrated in FIG. 1, the deionized water isreprocessed as follows. The deionized water from sixth stage 28 ispassed through line 88 to a filtration zone 90 which removes any solidor semi-solid materials present in this deionized water. The filtereddeionized water is passed through line 92 into water activated zone 94where the deionized water is contacted with activated carbon to removeextractable material (that has been removed from the contact lenses)present in the deionized water. The deionized water is then passedthrough line 95 to an ultraviolet (UV) light system 96 which irradiatesthe water and eliminates microbial contamination. Fresh, make-updeionized water is also introduced into line 95 and UV system 96. Toprevent the deionized water becoming contaminated by IMS from carry overfrom fifth stage 26, fresh deionized water is added continually and aportion of the liquid from sixth stage 28 is weired to waste. Typicallysuch portion is in a range of about 25% and about 90% of the tankvolume.

The deionized water is then passed, for example, by weiring, throughline 98 into eighth stage 32, through seventh stage 30, through sixthstage 28, and back to filtration zone 90.

Such reprocessing of the deionized water reduces the overall requirementfor deionized water in treating the contact lenses.

Such liquid processing reduces the requirement for IMS by at least about70% or about 80% or about 90%; and the requirement for deionized waterby about 10% to about 75%.

In short, the present systems provide for very effective removal ofextractable material from newly formed contact lenses and effectivehydration of the product contact lenses so that such contact lenses areavailable for packaging for safe and comfortable wear by lens wearers.In addition, the reprocessing of extraction media and other fluids,e.g., IMS and deionized water, used in such contact lens treating costeffectively reduces the amount of extraction media and the other fluidsrequired to treat the contact lenses. Reducing such requirements reducesthe adverse environmental impact of such contact lens processing andreduces the costs of such contact lens processing.

The present invention is also directed to methods of heat stabilizing acontact lens and contact lenses including a heat stabilizing component.

Generally, the method includes contacting a water swellable contact lenswith a material comprising a carrier component other than pure water,and a heat stabilizer component soluble in the carrier component andinsoluble in the contact lens in a hydrated state. The contacting iseffective to swell the contact lens with the material comprising thecarrier component and heat stabilizing component. The material swelledcontact lens is contacted with water at conditions effective to replaceat least a portion, for example, a major portion, and even substantiallyall, of the carrier component in the contact lens with water, therebyforming a water swelled contact lens including an effective amount ofthe heat stabilizer component.

The present invention provides such contact lenses which comprise a lensbody including a polymeric material and a heat stabilizer component. Forexample, a contact lens is provided comprising a lens body comprising ahydrophilic silicon-containing polymeric material and a heat stabilizercomponent. The heat stabilizer component is combined in the lens body inan amount effective to increase the heat stability of the contact lensrelative to an identical contact lens without the heat stabilizercomponent. Advantageously, the heat stabilizer component is insoluble inthe lens body in a hydrated state.

For example, a newly formed contact lens can be heat stabilized bycontacting the lens with a material, for example a liquid medium,comprising a carrier component other than pure water, and a heatstabilizer component. The heat stabilizer component is soluble in thecarrier component and insoluble in the contact lens in a hydrated state.The contacting is effective to swell the contact lens with the material.Next, the material swelled contact lens is then contacted with water atconditions effective to replace at least a portion, for example, a majorportion, and even substantially all, of the carrier component in thecontact lens with water, thereby forming a water swelled contact lensincluding an effective amount of the heat stabilizer componentincorporated in the lens.

More specifically, the contact lens comprises a hydrophilic polymericmaterial, for example, a hydrogel-forming polymeric material, ahydrophilic silicon-containing polymeric material and the like. The heatstabilizer component comprises a Vitamin E component. The carriercomponent comprises a component in which Vitamin E is substantially orsubstantially entirely soluble. The carrier component comprises, forexample a non-aqueous component, for example, an alcohol component. Thecarrier component preferably includes a material selected from methanol,ethanol, propanol and the like and mixtures thereof.

The heat stabilizer component is useful in certain embodiments, such ascertain embodiments of silicone hydrogel contact lenses, in that it issubstantially insoluble in the lens body in a hydrated state, that is,when the lens body is swelled with water. As discussed elsewhere herein,for example with respect to stage 24 in the processing system 10 shownin FIG. 1, the heat stabilizer component may comprise a Vitamin Ecomponent. The Vitamin E component may be selected from Vitamin E, saltsof Vitamin E, derivatives of Vitamin E, and mixtures thereof. In a veryuseful embodiment, the Vitamin E component comprises Vitamin E.

A method of heat stabilizing a contact lens comprises for example,contacting a lens, for example a hydrophilic silicon containing lenswith a first liquid medium comprising an IMS component and a Vitamin Ecomponent, at conditions effective to cause the lens to become swelledwith the first liquid medium. The first liquid medium comprises forexample a solution of an extraction medium containing about 80% to about90%, or greater IMS, for example about 95% IMS and about 10% to about20% or less by weight of water, and an effective amount of Vitamin E. Insome embodiments of the invention, the first liquid medium comprisesabout 90%-95% IMS and about 5%-10% water and an effective amount ofVitamin E.

After the contacting with the first liquid medium, the lens, which isnow swelled with the first liquid medium containing Vitamin E in asoluble state, is then contacted with a second liquid medium whichrenders the Vitamin E substantially insoluble. The second liquid mediumcomprises a substantial amount of water, for example, at least about 50%deionized water. Some of the carrier component held in the lens isreplaced with water while most or all of the Vitamin E in the lensremains in the lens. The swelled lens is then moved to another stagewhere it is contacted with pure deionized water. As the Vitamin E isinsoluble in water, the water, for example deionized water, replaces thefirst liquid medium in the lens, without substantially removing any ofthe heat stabilizing component from the lens. This stage may occur atbetween about 20° C. to about 25° C.

In some embodiments of the present methods, the now hydrated lenscontaining the heat stabilizing component, (e.g. Vitamin E) istransferred to another stage in which the hydrated, heat stabilized lensis contacted with a third liquid medium comprising deionized water and asuitable buffer component and/or suitable tonicity component.

A preferred embodiment of the invention for processing lenses and isshown and generally described with respect to FIG. 2. Except asexpressly described herein, system 110 is similar to system 10 andfeatures of system 110 which correspond to features of system 10 aredesignated by the corresponding reference numerals increased by 100. Inother words, stages 112, 116, 120, 126 and 128 are essentially the sameas stages 12, 16, 20, 26 and 28, respectively.

System 110 is substantially the same as system 10, with the primarydifference being that stage 24, which includes contacting the lenseswith a heat stabilizing solution, such as a solution including VitaminE, is absent, and the contact lenses from third stage 120 are passeddirectly to fifth stage 126 . Although not shown, in an alternativeembodiment, another Stage is provided between third stage 120 and fifthstage 126, which may be a repeat of stage 120.

With reference to FIG. 2, newly formed swellable, polymeric contactlenses, for example, such lenses containing a hydrophilic,silicon-containing polymeric material, are processed in system 110. Suchlenses are provided to first system 112 of system 110. These lensesinclude unreacted monomers, and possibly other extractable material,which are to be removed before the lenses can be packaged forshipment/sale.

In first stage 112, the lenses are contacted with a liquid compositioncontaining about 80% to about 90% IMS and about 10% to about 20% byweight of water. Such contacting occurs at a temperature in a range ofabout 20° C. to about 50° C. The operating temperatures of first stage112, as well as second, third, fifth and sixth stages 116, 120 , 126 and128 , are in a range of about 20° C. to about 50° C. These stages may beenclosed within a common module or enclosure for safety reasons. Seventhand eighth stage 130 and 132 are operated at less than about 25° C., forexample, at ambient or room temperature.

As in system 10, ultrasonic energy, produced using a conventionalultrasonic energy generator, may optionally be applied to the liquidcomposition in any one or more of stages 112, 116, 120, 126 and 128, tofacilitate intimate contacting between the liquid composition and thecontact lenses in such stages.

Intimate contacting between the liquid composition and contact lensesmay be facilitated through continuous liquid composition agitation fromthe continuous topping of the tank and continuous draining of the liquidcomposition from the tank via a conventional weir system.

Preferably, intimate contacting between the liquid composition and thecontact lenses is obtained in first stage 112 so that the lenses becomeswelled with the liquid composition and mass transfer occurs between thelenses and the liquid composition. Some of the extractable materialoriginally in or on the lenses is removed from the lenses in firstsystem 112 and is present in the liquid composition outside the lenses.

During and after such contacting, the liquid composition in first system112 may optionally be pumped through a first activated zone 114 whichcontains activated carbon. The liquid composition from the first system112 may be passed through the activated carbon in first activated zone114 and passed back into first stage 112. The activated carbon in firstactivated zone 114 removes some of the extractable material which isremoved from the contact lenses in first stage 112, and thus helps toprolong the effectiveness of the liquid composition in first stage 112.

First stage 112, like the other stages described hereinafter (unlessexpressly stated otherwise), may be equipped with at least one pump, forexample, of conventional design, to pass the liquid in first system 112through first activated zone 114 and/or to pump the liquid out of firstsystem 112 for reprocessing, for example, if the lens treating whichoccurs in the stage is conducted in a batch-wise mode with respect tothe treating liquid or liquids being employed as is described elsewhereherein. Such pumping action also facilitates intimate contacting betweenthe liquid and contact lenses in first stage 112.

The stages for processing and reprocessing of the extraction media anddeionized water used in system 110 are essentially the same as describedhereinabove with respect to system 10.

For example, after it is determined that the used or spent compositionin system 112 is no longer suitable for effective/efficient functioningin first system 112 and, therefore, is to be removed and replaced, theliquid composition from system 112 is passed out of first system 112 andpassed through line 134 into common line 136. Similarly, the used orspent liquid material from stages 116, 120 and 126 are passed out ofthese stages, through lines 138, 140 and 144, respectively, into commonline 136.

The liquid passing through common line 136 is brought into contact witha conventional micro porous filter medium in filter zone 150 effectiveto remove lens debris and/or other solid or semi-solid debris and/orextraneous material from the system 110.

The filtered liquid is passed from filter zone 150 through line 152 intocommon activated zone 154 where the liquid is contacted with activatedcarbon to remove extractable material (previously removed from thecontact lenses) from the liquid which is then passed through line 155 toa storage tank 156.

The liquid from storage tank 156 is passed through line 158 intodistillation zone 160 where the liquid is separated into an eutecticcomposition containing about 95% by weight IMS and about 5% by weight ofwater, and an aqueous waste product, which is properly disposed of afterbeing removed from distillation zone through line 162.

Distillation zone 160 comprises a conventional, and advantageously fullyautomatic, distillation apparatus in which a low boiling material, suchas the composition containing about 95% by weight IMS, is the overheadproduct, and the higher boiling material, such as the aqueous wasteproduct, is removed from the bottom of the apparatus. A portion of theliquid containing about 95% by weight IMS is passed through line 164into storage tank 166.

The remainder of the liquid containing about 95% by weight IMS fromdistillation zone 160 is passed through line 168 into a drying device170 to remove water from this liquid and produce a product liquid havingat least about 99% by weight IMS. This product liquid containing atleast about 99% IMS is passed through line 172 to storage tank 174.

A quantity of fresh liquid IMS is added to storage tank 174. This freshIMS is added to make up for the IMS that is lost during the treating ofthe contact lenses and the reprocessing of the liquids used in suchtreating.

Liquids in storage tanks 166 and 174 are passed to the individual stages112, 116, 120, and 126 to provide the desired liquid composition/liquidmaterial for each such stage.

Like system 10, the combination of filtration, activated carboncontacting, distillation, and drying, together with separate storage ofdifferent liquids having different IMS concentrations, provide for veryeffective removal of extractable material from the contact lenses and,at the same time, because of the reprocessing of the liquidcompositions/materials as noted above, reduces the overall amount of IMSrequired to perform such treating.

The deionized water may be reprocessed as follows. The deionized waterfrom stage 128 is passed through line 188 to a filtration zone 190 whichremoves solid and/or semi-solid materials present in this deionizedwater. The filtered deionized water is passed through line 192 intowater activated zone 194 where the deionized water is contacted withactivated carbon to remove extractable material present in the deionizedwater. The deionized water is then passed through line 195 to anultraviolet (UV) light system 196 which irradiates the water andeliminates microbial contamination. Fresh, make-up deionized water isalso introduced into line 195 and UV system 196. The deionized water isthen passed, for example, by weiring, through line 198 into stage 132,through stage 130, through stage 128, and back to filtration zone 190.

Such reprocessing of the deionized water reduces the overall requirementfor deionized water in treating the contact lenses.

Such liquid processing reduces the requirement for IMS by at least about70% or about 80% or about 90%; and the requirement for deionized waterby about 10% to about 75%.

The present invention may be more clearly understood with reference tothe following non-limiting Examples.

EXAMPLE 1

A newly formed contact lens containing a hydrophilic, silicon-containingpolymeric material is contacted with an extraction medium containingindustrial methylated spirits (IMS), containing 97% by weight ethanoland 3% by weight methanol. In addition, the extraction medium contains asmall amount of water, for example, less than 5% by weight of the totalextraction medium. This contacting occurs for about 30-45 minutes at atemperature ranging from about 25° C. to about 50° C. Ultrasonic energyis applied during this contacting to agitate the extractive medium. Thiscontacting results in the removal of undesirable extractable material,such as unreacted monomers, from the newly formed contact lens. Inaddition, the contacting results in the contact lens becoming swelledwith the extraction medium.

This swelled contact lens is then contacted with a first liquid mediumcontaining a different portion of the extraction medium. The liquidmedium also includes 100 ppm by weight of Vitamin E, which is soluble inthe liquid medium. This contacting occurs for 30 minutes at atemperature of less than about 25° C., for example, about 20° C., orroom temperature. Ultrasonic energy is applied during this contacting toagitate the liquid medium so as to facilitate replacing the extractionmedium with the liquid medium in the contact lens. The resulting contactlens is swelled with the first liquid medium containing Vitamin E.

In the next stage of processing, the resulting swelled contact lens isthen contacted with a second liquid medium of substantially puredeionized water. This contacting occurs for 30 minutes at a temperatureof less than 25° C., for example, about 20° C., or room temperature.Ultrasonic energy is applied during this contacting to agitate thesecond liquid medium so as to facilitate replacing the first liquidmedium with the second liquid medium in the contact lens.

The contact lens produced by this processing is swelled with the secondliquid medium. However, since Vitamin E is insoluble in the deionizedwater of the second liquid medium, the produced, swelled contact lensalso contains an effective, heat stabilizing amount of Vitamin E.

A final contacting step is conducted using a third liquid mediumcomprising deionized water, a suitable buffer component and a suitabletonicity component. Such contacting occurs for about 30 minutes at roomtemperature with the application of ultrasonic energy to facilitatereplacing the second liquid medium with the third liquid medium in thecontact lens. This contacting provides a water swelled contact lensproduct containing an effective, heat stabilizing amount of Vitamin E.This water swelled contact lens product is ready for packaging in aconventional blister package.

EXAMPLE 2

Example 1 is repeated except that, before the contacting with swelledcontact lens, swelled with the first liquid medium, is contacted with afurther liquid medium comprising 50% by weight of IMS and 50% by weightdeionized water. This contacting occurs for 30 minutes at a temperatureof less than about 25° C., for example, about 20° C. or roomtemperature. Ultrasonic energy is applied during this contacting toagitate the further liquid medium so as to facilitate replacing thefirst liquid medium with the further liquid medium in the contact lens.The contact lens produced by this processing is swelled with the furtherliquid medium. This swelled contact lens also contains an effective,heat stabilizing amount of Vitamin E since Vitamin E is largelyinsoluble in the further liquid medium. In this embodiment it may beadvantageous to have a somewhat larger amount of Vitamin E present inthe contact lens swelled with the first liquid medium since some of theVitamin E may be removed from the contact lens during the contactingwith the further liquid medium.

Using the further liquid medium in an intermediate contacting stepbetween contacting the contact lens with the first liquid medium andcontacting the contact lens with the second liquid medium, for example,as described in this Example 2, may reduce stress on the lens and/ordamage to the lens caused by an abrupt change in environment from asubstantially alcoholic liquid medium (first liquid medium) to asubstantially aqueous medium (second liquid medium).

In any event, the further liquid medium swelled contact lens iscontacted with the second liquid medium in substantially the same way asthe first liquid medium swelled contact lens is contacted with thesecond liquid medium as described in Example 1.

Ultimately, this processing provides a swelled contact lens productcontaining an effective, heat stabilizing amount of Vitamin E ready forpackaging in a conventional blister package.

EXAMPLES 3 AND 4

Examples 1 and 2, respectively, are repeated except that, in each case,the single contact lens is replaced by 500 contact lenses with each lensbeing located in a space between two trays suitably structured to allowfor effective contacting and mass exchange or transfer between thecontact lens and the processing fluids.

Ultimately, each processing sequence, that is each of the series ofsteps described in Examples 1 and 2, provides 500 swelled contact lenseseach of which contains an effective heat stabilizing amount of Vitamin Eready for packaging in a conventional blister package.

EXAMPLE 5

Example 1 is repeated except that, instead of the step of contacting thelenses with a liquid medium including Vitamin E, the lenses are insteadcontacted with a liquid medium comprising about 95% by weight of IMS andabout 5% by weight deionized water and no Vitamin E, prior to the stepof being contacted with a liquid medium comprising 50% by weight IMS andabout 50% by weight deionized water.

Since Vitamin E is not employed in this example, this particular methodis especially useful for lenses made of polymeric compositions that donot require heat stabilization.

Thus, it may be understood from the disclosure herein, that lenses, suchas silicon hydrogel contact lenses, that have been removed fromindividual lens molds may be placed in individual wells of coloredtrays. Each tray can hold 32 lenses. The trays are stacked upon eachother and placed on or in cartridges. Each cartridge can contain 48trays, and accordingly, each cartridge can contain 1536 contact lenses.

A cartridge containing the trays and lenses may be placed in a washingstation or stage. In that regard, one embodiment of the present systemscomprises four extraction stations, or four stations containing asolvent based extraction medium, and two hydration stations containingsubstantial amounts of water. The system also comprises two roboticarms. A cartridge is placed in the first extraction station using arobotic arm. The first extraction station comprises an extraction mediumcomprising about 90-95% IMS (ethanol/methanol blend) and 5-10% water.The cartridge and lenses are left in the first station for about 45minutes. A robotic arm then removes the cartridge from the first stationand places the cartridge in the second station for about 45 minutes. Thesecond station comprises an extraction media which comprises at least95% IMS. The robotic arm then removes the cartridge from the secondstation to the third station which contains at least 95% IMS. Therobotic arm than removes the cartridge from the third station and placesit in the fourth station which comprises an extraction medium of atleast 99% IMS. The cartridge is removed from the fourth station by therobotic arm and placed in the fifth station which comprises anintermediate extraction/hydration medium of 50% IMS and 50% deionizedwater (plus or minus 10% ). The robotic arm then removes the cartridgefrom the fifth station and places the cartridge in the sixth stationcontaining at least 99% deionized water and less than 1% IMS.

As discussed herein, optionally, and depending on the particularpolymeric material from which the lenses are formed, vitamin E can beprovided at station 4 in the above embodiment.

The media of the present systems is recycled, as discussed herein. Somevolume of the media may be lost due to the recycling process. Typically,this loss is less than about five liters per hour. Therefore, it may bedesirable to refresh one or more of the stations by adding freshextraction media to the media contained in the stations. As one example,a method may comprise a step of adding about 25% of new extraction mediato the used extraction media.

The present systems can extract and hydrate silicone hydrogel contactlenses and prepare them for packaging within about six hours from theinitial extraction step, and in certain embodiments, the entire processcan be performed in less than about two to three hours.

During the process, the system is vented using one or more vents toreduce the possibility of damage caused by IMS vapors. In addition, thesystems and methods may maintain the ambient temperature at levels toreduce IMS vaporization and flammability.

Using the present systems, approximately 99.9% of the IMS can berecycled thereby resulting in substantial cost savings relative toexisting systems which discard the organic solvents during theextraction process.

Certain aspects and advantages of the present invention may be moreclearly understood and/or appreciated with reference to the followingcommonly owned United States Patent Applications, filed on even dateherewith, the disclosure of each of which is being incorporated hereinin its entirety by this specific reference: U.S. patent application Ser.No. 11/200,848, entitled “Contact Lens Molds and Systems and Methods forProducing Same”, U.S. patent application Ser. No. 11/200,648, entitled“Contact Lens Mold Assemblies and Systems and Methods of ProducingSame”; U.S. patent application Ser. No. 11/200,644, entitled “Systemsand Methods for Producing Contact Lenses from a PolymerizableComposition”U.S. patent application Ser. No. 11/201,410, entitled“Systems and Methods for Removing Lenses from Lens Molds”, U.S. patentapplication Ser. No. 11/200,862, entitled “Contact Lens Package”, U.S.patent application Ser. No. 60/707,029, entitled “Compositions andMethods for Producing Silicone Hydrogel Contact Lenses”, and U.S. patentapplication Ser. No. 11/201,409, entitled “Systems and Methods forProducing Silicone Hydrogel Contact Lenses”.

1. A method for treating a contact lens comprising: (a) contacting aswellable, polymeric contact lens containing extractable material withan extraction medium comprising water in an amount of less than 100% atconditions effective to swell the contact lens with the extractionmedium, to reduce the amount of extractable material in the contactlens, and to form a used extraction medium containing extractablematerial; (b) contacting the contact lens having a reduced amount ofextractable material with water to form a water swelled contact lens;(c) processing the used extraction medium to produce a reprocessedextraction medium having a reduced concentration of extractable materialrelative to the used extraction medium; and (d) using the reprocessedextraction medium as at least a portion of the extraction medium in step(a).
 2. The method of claim 1 wherein step (a) is repeated at leastonce.
 3. The method of claim 1 wherein the extraction medium includesless than about 15% by weight of water, the water in the extractionmedium being effective in reducing stress on the contact lens.
 4. Themethod of claim 1 wherein step (a) is conducted at conditions so thatthe amount of extractable material in the contact lens is reduced by atleast about 90%.
 5. The method of claim 1 wherein the extraction mediumcomprises an alcohol.
 6. The method of claim 1 wherein the extractionmedium comprises an alcohol selected from the group consisting ofmethanol, ethanol, propanol and mixtures thereof.
 7. The method of claim1 wherein the extraction medium comprises a major amount by weight ofethanol on a water-free basis.
 8. The method of claim 1 wherein thecontact lens comprises a hydrophilic silicon-containing polymer.
 9. Themethod of claim 1 wherein step (a) includes contacting the contact lenswith a first extraction medium portion and, thereafter, contacting thecontact lens with a second extraction medium portion having a reducedconcentration of water relative to the first extraction medium portion.10. A method for reprocessing an extraction medium used in removingextractable material from a polymeric contact lens comprising: (1)contacting a used extraction medium comprising water in an amount ofless than 100% and extractable material from a polymeric contact lens atconditions effective to produce a first product having a reduced contentof water and a reduced content of the extractable material relative tothe used extraction medium; and, thereafter, (2) contacting at least aportion of the first product at conditions effective to produce a secondproduct having a reduced content of water relative to the first product.11. The method of claim 10 which further comprises contacting a portionof the first product with a polymeric contact lens containingextractable material at conditions effective to remove at least aportion of the extractable material from the polymeric contact lens,thereby forming a first contact lens product having a reduced amount ofextractable material relative to the polymeric contact lens, and to format least a portion of the used extraction medium.
 12. The method ofclaim 11 which further comprises contacting at least a portion of thesecond product with the first contact lens product at conditionseffective to extract an additional amount of the extractable materialfrom the first contact lens product, thereby forming a second contactlens product having a reduced amount of extractable material relative tothe first contact lens product, and to form another portion of the usedextraction medium.
 13. The method of claim 12 which further comprisescontacting a portion of the first product with the second contact lensproduct in the presence of water at conditions effective to partiallyhydrate the second contact lens product, thereby forming a firsthydrated contact lens, and an additional portion of the used extractionmedium.
 14. The method of claim 10 which further comprises, prior tostep (1), contacting at least a portion of the used extraction mediumwith a filter medium at conditions effective to remove contact lensdebris from the used extraction medium.
 15. The method of claim 14wherein step (1) includes contacting at least a portion of the usedextraction medium with an adsorption medium at conditions effective toremove at least a portion of the extractable material from the usedextraction medium.
 16. The method of claim 15 wherein the filter mediumcontacting occurs prior to the adsorption medium contacting.
 17. Themethod of claim 10 wherein the used extraction medium includes a majoramount of an alcohol component.
 18. A contact lens comprising: a formedwater swellable, polymeric lens body; and a heat stabilizer componentfirst introduced into the formed lens body in an amount effective toincrease the heat stability of the contact lens relative to an identicalcontact lens without the heat stabilizer component, the heat stabilizercomponent being insoluble in the formed lens body in a hydrated state.19. The contact lens of claim 18 wherein the formed lens body comprisesa hydrophilic silicon-containing polymeric material.
 20. The contactlens of claim 18 wherein the heat stabilizing component is selected fromthe group consisting of vitamin E, salts of vitamin E, derivatives ofvitamin E and mixtures thereof.
 21. The method of claim 9 wherein thewater in the first extraction medium portion being effective in reducingthe risk of damaging the contact lens.
 22. The contact lens of claim 18wherein the heat stabilizing component comprises Vitamin E.